/*
 * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "server.h"
#include "sha1.h"   /* SHA1 is used for DEBUG DIGEST */
#include "crc64.h"

#include <arpa/inet.h>
#include <signal.h>
#include <dlfcn.h>

#ifdef HAVE_BACKTRACE
#include <execinfo.h>
#ifndef __OpenBSD__
#include <ucontext.h>
#else
typedef ucontext_t sigcontext_t;
#endif
#include <fcntl.h>
#include "bio.h"
#include <unistd.h>
#endif /* HAVE_BACKTRACE */

#ifdef __CYGWIN__
#ifndef SA_ONSTACK
#define SA_ONSTACK 0x08000000
#endif
#endif

/* ================================= Debugging ============================== */

/* Compute the sha1 of string at 's' with 'len' bytes long.
 * The SHA1 is then xored against the string pointed by digest.
 * Since xor is commutative, this operation is used in order to
 * "add" digests relative to unordered elements.
 *
 * So digest(a,b,c,d) will be the same of digest(b,a,c,d) */
void xorDigest(unsigned char *digest, void *ptr, size_t len) {
    SHA1_CTX ctx;
    unsigned char hash[20], *s = ptr;
    int j;

    SHA1Init(&ctx);
    SHA1Update(&ctx,s,len);
    SHA1Final(hash,&ctx);

    for (j = 0; j < 20; j++)
        digest[j] ^= hash[j];
}

void xorStringObjectDigest(unsigned char *digest, robj *o) {
    o = getDecodedObject(o);
    xorDigest(digest,o->ptr,sdslen(o->ptr));
    decrRefCount(o);
}

/* This function instead of just computing the SHA1 and xoring it
 * against digest, also perform the digest of "digest" itself and
 * replace the old value with the new one.
 *
 * So the final digest will be:
 *
 * digest = SHA1(digest xor SHA1(data))
 *
 * This function is used every time we want to preserve the order so
 * that digest(a,b,c,d) will be different than digest(b,c,d,a)
 *
 * Also note that mixdigest("foo") followed by mixdigest("bar")
 * will lead to a different digest compared to "fo", "obar".
 */
void mixDigest(unsigned char *digest, void *ptr, size_t len) {
    SHA1_CTX ctx;
    char *s = ptr;

    xorDigest(digest,s,len);
    SHA1Init(&ctx);
    SHA1Update(&ctx,digest,20);
    SHA1Final(digest,&ctx);
}

void mixStringObjectDigest(unsigned char *digest, robj *o) {
    o = getDecodedObject(o);
    mixDigest(digest,o->ptr,sdslen(o->ptr));
    decrRefCount(o);
}

/* This function computes the digest of a data structure stored in the
 * object 'o'. It is the core of the DEBUG DIGEST command: when taking the
 * digest of a whole dataset, we take the digest of the key and the value
 * pair, and xor all those together.
 *
 * Note that this function does not reset the initial 'digest' passed, it
 * will continue mixing this object digest to anything that was already
 * present. */
void xorObjectDigest(redisDb *db, robj *keyobj, unsigned char *digest, robj *o) {
    uint32_t aux = htonl(o->type);
    mixDigest(digest,&aux,sizeof(aux));
    long long expiretime = getExpire(db,keyobj);
    char buf[128];

    /* Save the key and associated value */
    if (o->type == OBJ_STRING) {
        mixStringObjectDigest(digest,o);
    } else if (o->type == OBJ_LIST) {
        listTypeIterator *li = listTypeInitIterator(o,0,LIST_TAIL);
        listTypeEntry entry;
        while(listTypeNext(li,&entry)) {
            robj *eleobj = listTypeGet(&entry);
            mixStringObjectDigest(digest,eleobj);
            decrRefCount(eleobj);
        }
        listTypeReleaseIterator(li);
    } else if (o->type == OBJ_SET) {
        setTypeIterator *si = setTypeInitIterator(o);
        sds sdsele;
        while((sdsele = setTypeNextObject(si)) != NULL) {
            xorDigest(digest,sdsele,sdslen(sdsele));
            sdsfree(sdsele);
        }
        setTypeReleaseIterator(si);
    } else if (o->type == OBJ_ZSET) {
        unsigned char eledigest[20];

        if (o->encoding == OBJ_ENCODING_ZIPLIST) {
            unsigned char *zl = o->ptr;
            unsigned char *eptr, *sptr;
            unsigned char *vstr;
            unsigned int vlen;
            long long vll;
            double score;

            eptr = ziplistIndex(zl,0);
            serverAssert(eptr != NULL);
            sptr = ziplistNext(zl,eptr);
            serverAssert(sptr != NULL);

            while (eptr != NULL) {
                serverAssert(ziplistGet(eptr,&vstr,&vlen,&vll));
                score = zzlGetScore(sptr);

                memset(eledigest,0,20);
                if (vstr != NULL) {
                    mixDigest(eledigest,vstr,vlen);
                } else {
                    ll2string(buf,sizeof(buf),vll);
                    mixDigest(eledigest,buf,strlen(buf));
                }

                snprintf(buf,sizeof(buf),"%.17g",score);
                mixDigest(eledigest,buf,strlen(buf));
                xorDigest(digest,eledigest,20);
                zzlNext(zl,&eptr,&sptr);
            }
        } else if (o->encoding == OBJ_ENCODING_SKIPLIST) {
            zset *zs = o->ptr;
            dictIterator *di = dictGetIterator(zs->dict);
            dictEntry *de;

            while((de = dictNext(di)) != NULL) {
                sds sdsele = dictGetKey(de);
                double *score = dictGetVal(de);

                snprintf(buf,sizeof(buf),"%.17g",*score);
                memset(eledigest,0,20);
                mixDigest(eledigest,sdsele,sdslen(sdsele));
                mixDigest(eledigest,buf,strlen(buf));
                xorDigest(digest,eledigest,20);
            }
            dictReleaseIterator(di);
        } else {
            serverPanic("Unknown sorted set encoding");
        }
    } else if (o->type == OBJ_HASH) {
        hashTypeIterator *hi = hashTypeInitIterator(o);
        while (hashTypeNext(hi) != C_ERR) {
            unsigned char eledigest[20];
            sds sdsele;

            memset(eledigest,0,20);
            sdsele = hashTypeCurrentObjectNewSds(hi,OBJ_HASH_KEY);
            mixDigest(eledigest,sdsele,sdslen(sdsele));
            sdsfree(sdsele);
            sdsele = hashTypeCurrentObjectNewSds(hi,OBJ_HASH_VALUE);
            mixDigest(eledigest,sdsele,sdslen(sdsele));
            sdsfree(sdsele);
            xorDigest(digest,eledigest,20);
        }
        hashTypeReleaseIterator(hi);
    } else if (o->type == OBJ_STREAM) {
        streamIterator si;
        streamIteratorStart(&si,o->ptr,NULL,NULL,0);
        streamID id;
        int64_t numfields;

        while(streamIteratorGetID(&si,&id,&numfields)) {
            sds itemid = sdscatfmt(sdsempty(),"%U.%U",id.ms,id.seq);
            mixDigest(digest,itemid,sdslen(itemid));
            sdsfree(itemid);

            while(numfields--) {
                unsigned char *field, *value;
                int64_t field_len, value_len;
                streamIteratorGetField(&si,&field,&value,
                                           &field_len,&value_len);
                mixDigest(digest,field,field_len);
                mixDigest(digest,value,value_len);
            }
        }
        streamIteratorStop(&si);
    } else if (o->type == OBJ_MODULE) {
        RedisModuleDigest md;
        moduleValue *mv = o->ptr;
        moduleType *mt = mv->type;
        moduleInitDigestContext(md);
        if (mt->digest) {
            mt->digest(&md,mv->value);
            xorDigest(digest,md.x,sizeof(md.x));
        }
    } else {
        serverPanic("Unknown object type");
    }
    /* If the key has an expire, add it to the mix */
    if (expiretime != -1) xorDigest(digest,"!!expire!!",10);
}

/* Compute the dataset digest. Since keys, sets elements, hashes elements
 * are not ordered, we use a trick: every aggregate digest is the xor
 * of the digests of their elements. This way the order will not change
 * the result. For list instead we use a feedback entering the output digest
 * as input in order to ensure that a different ordered list will result in
 * a different digest. */
void computeDatasetDigest(unsigned char *final) {
    unsigned char digest[20];
    dictIterator *di = NULL;
    dictEntry *de;
    int j;
    uint32_t aux;

    memset(final,0,20); /* Start with a clean result */

    for (j = 0; j < server.dbnum; j++) {
        redisDb *db = server.db+j;

        if (dictSize(db->dict) == 0) continue;
        di = dictGetSafeIterator(db->dict);

        /* hash the DB id, so the same dataset moved in a different
         * DB will lead to a different digest */
        aux = htonl(j);
        mixDigest(final,&aux,sizeof(aux));

        /* Iterate this DB writing every entry */
        while((de = dictNext(di)) != NULL) {
            sds key;
            robj *keyobj, *o;

            memset(digest,0,20); /* This key-val digest */
            key = dictGetKey(de);
            keyobj = createStringObject(key,sdslen(key));

            mixDigest(digest,key,sdslen(key));

            o = dictGetVal(de);
            xorObjectDigest(db,keyobj,digest,o);

            /* We can finally xor the key-val digest to the final digest */
            xorDigest(final,digest,20);
            decrRefCount(keyobj);
        }
        dictReleaseIterator(di);
    }
}

#ifdef USE_JEMALLOC
void mallctl_int(client *c, robj **argv, int argc) {
    int ret;
    /* start with the biggest size (int64), and if that fails, try smaller sizes (int32, bool) */
    int64_t old = 0, val;
    if (argc > 1) {
        long long ll;
        if (getLongLongFromObjectOrReply(c, argv[1], &ll, NULL) != C_OK)
            return;
        val = ll;
    }
    size_t sz = sizeof(old);
    while (sz > 0) {
        if ((ret=je_mallctl(argv[0]->ptr, &old, &sz, argc > 1? &val: NULL, argc > 1?sz: 0))) {
            if (ret == EPERM && argc > 1) {
                /* if this option is write only, try just writing to it. */
                if (!(ret=je_mallctl(argv[0]->ptr, NULL, 0, &val, sz))) {
                    addReply(c, shared.ok);
                    return;
                }
            }
            if (ret==EINVAL) {
                /* size might be wrong, try a smaller one */
                sz /= 2;
#if BYTE_ORDER == BIG_ENDIAN
                val <<= 8*sz;
#endif
                continue;
            }
            addReplyErrorFormat(c,"%s", strerror(ret));
            return;
        } else {
#if BYTE_ORDER == BIG_ENDIAN
            old >>= 64 - 8*sz;
#endif
            addReplyLongLong(c, old);
            return;
        }
    }
    addReplyErrorFormat(c,"%s", strerror(EINVAL));
}

void mallctl_string(client *c, robj **argv, int argc) {
    int rret, wret;
    char *old;
    size_t sz = sizeof(old);
    /* for strings, it seems we need to first get the old value, before overriding it. */
    if ((rret=je_mallctl(argv[0]->ptr, &old, &sz, NULL, 0))) {
        /* return error unless this option is write only. */
        if (!(rret == EPERM && argc > 1)) {
            addReplyErrorFormat(c,"%s", strerror(rret));
            return;
        }
    }
    if(argc > 1) {
        char *val = argv[1]->ptr;
        char **valref = &val;
        if ((!strcmp(val,"VOID")))
            valref = NULL, sz = 0;
        wret = je_mallctl(argv[0]->ptr, NULL, 0, valref, sz);
    }
    if (!rret)
        addReplyBulkCString(c, old);
    else if (wret)
        addReplyErrorFormat(c,"%s", strerror(wret));
    else
        addReply(c, shared.ok);
}
#endif

void debugCommand(client *c) {
    if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"help")) {
        const char *help[] = {
"ASSERT -- Crash by assertion failed.",
"CHANGE-REPL-ID -- Change the replication IDs of the instance. Dangerous, should be used only for testing the replication subsystem.",
"CRASH-AND-RECOVER <milliseconds> -- Hard crash and restart after <milliseconds> delay.",
"DIGEST -- Output a hex signature representing the current DB content.",
"DIGEST-VALUE <key-1> ... <key-N>-- Output a hex signature of the values of all the specified keys.",
"DEBUG PROTOCOL [string|integer|double|bignum|null|array|set|map|attrib|push|verbatim|true|false]",
"ERROR <string> -- Return a Redis protocol error with <string> as message. Useful for clients unit tests to simulate Redis errors.",
"LOG <message> -- write message to the server log.",
"LEAK <string> -- Create a memory leak of the input string.",
"HTSTATS <dbid> -- Return hash table statistics of the specified Redis database.",
"HTSTATS-KEY <key> -- Like htstats but for the hash table stored as key's value.",
"LOADAOF -- Flush the AOF buffers on disk and reload the AOF in memory.",
"LUA-ALWAYS-REPLICATE-COMMANDS <0|1> -- Setting it to 1 makes Lua replication defaulting to replicating single commands, without the script having to enable effects replication.",
"OBJECT <key> -- Show low level info about key and associated value.",
"OOM -- Crash the server simulating an out-of-memory error.",
"PANIC -- Crash the server simulating a panic.",
"POPULATE <count> [prefix] [size] -- Create <count> string keys named key:<num>. If a prefix is specified is used instead of the 'key' prefix.",
"RELOAD [MERGE] [NOFLUSH] [NOSAVE] -- Save the RDB on disk and reload it back in memory. By default it will save the RDB file and load it back. With the NOFLUSH option the current database is not removed before loading the new one, but conficts in keys will kill the server with an exception. When MERGE is used, conflicting keys will be loaded (the key in the loaded RDB file will win). When NOSAVE is used, the server will not save the current dataset in the RDB file before loading. Use DEBUG RELOAD NOSAVE when you want just to load the RDB file you placed in the Redis working directory in order to replace the current dataset in memory. Use DEBUG RELOAD NOSAVE NOFLUSH MERGE when you want to add what is in the current RDB file placed in the Redis current directory, with the current memory content. Use DEBUG RELOAD when you want to verify Redis is able to persist the current dataset in the RDB file, flush the memory content, and load it back.",
"RESTART -- Graceful restart: save config, db, restart.",
"SDSLEN <key> -- Show low level SDS string info representing key and value.",
"SEGFAULT -- Crash the server with sigsegv.",
"SET-ACTIVE-EXPIRE <0|1> -- Setting it to 0 disables expiring keys in background when they are not accessed (otherwise the Redis behavior). Setting it to 1 reenables back the default.",
"AOF-FLUSH-SLEEP <microsec> -- Server will sleep before flushing the AOF, this is used for testing",
"SLEEP <seconds> -- Stop the server for <seconds>. Decimals allowed.",
"STRUCTSIZE -- Return the size of different Redis core C structures.",
"ZIPLIST <key> -- Show low level info about the ziplist encoding.",
"STRINGMATCH-TEST -- Run a fuzz tester against the stringmatchlen() function.",
#ifdef USE_JEMALLOC
"MALLCTL <key> [<val>] -- Get or set a malloc tunning integer.",
"MALLCTL-STR <key> [<val>] -- Get or set a malloc tunning string.",
#endif
NULL
        };
        addReplyHelp(c, help);
    } else if (!strcasecmp(c->argv[1]->ptr,"segfault")) {
        *((char*)-1) = 'x';
    } else if (!strcasecmp(c->argv[1]->ptr,"panic")) {
        serverPanic("DEBUG PANIC called at Unix time %ld", time(NULL));
    } else if (!strcasecmp(c->argv[1]->ptr,"restart") ||
               !strcasecmp(c->argv[1]->ptr,"crash-and-recover"))
    {
        long long delay = 0;
        if (c->argc >= 3) {
            if (getLongLongFromObjectOrReply(c, c->argv[2], &delay, NULL)
                != C_OK) return;
            if (delay < 0) delay = 0;
        }
        int flags = !strcasecmp(c->argv[1]->ptr,"restart") ?
            (RESTART_SERVER_GRACEFULLY|RESTART_SERVER_CONFIG_REWRITE) :
             RESTART_SERVER_NONE;
        restartServer(flags,delay);
        addReplyError(c,"failed to restart the server. Check server logs.");
    } else if (!strcasecmp(c->argv[1]->ptr,"oom")) {
        void *ptr = zmalloc(ULONG_MAX); /* Should trigger an out of memory. */
        zfree(ptr);
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"assert")) {
        serverAssertWithInfo(c,c->argv[0],1 == 2);
    } else if (!strcasecmp(c->argv[1]->ptr,"log") && c->argc == 3) {
        serverLog(LL_WARNING, "DEBUG LOG: %s", (char*)c->argv[2]->ptr);
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"leak") && c->argc == 3) {
        sdsdup(c->argv[2]->ptr);
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"reload")) {
        int flush = 1, save = 1;
        int flags = RDBFLAGS_NONE;

        /* Parse the additional options that modify the RELOAD
         * behavior. */
        for (int j = 2; j < c->argc; j++) {
            char *opt = c->argv[j]->ptr;
            if (!strcasecmp(opt,"MERGE")) {
                flags |= RDBFLAGS_ALLOW_DUP;
            } else if (!strcasecmp(opt,"NOFLUSH")) {
                flush = 0;
            } else if (!strcasecmp(opt,"NOSAVE")) {
                save = 0;
            } else {
                addReplyError(c,"DEBUG RELOAD only supports the "
                                "MERGE, NOFLUSH and NOSAVE options.");
                return;
            }
        }

        /* The default beahvior is to save the RDB file before loading
         * it back. */
        if (save) {
            rdbSaveInfo rsi, *rsiptr;
            rsiptr = rdbPopulateSaveInfo(&rsi);
            if (rdbSave(server.rdb_filename,rsiptr) != C_OK) {
                addReply(c,shared.err);
                return;
            }
        }

        /* The default behavior is to remove the current dataset from
         * memory before loading the RDB file, however when MERGE is
         * used together with NOFLUSH, we are able to merge two datasets. */
        if (flush) emptyDb(-1,EMPTYDB_NO_FLAGS,NULL);

        protectClient(c);
        int ret = rdbLoad(server.rdb_filename,NULL,flags);
        unprotectClient(c);
        if (ret != C_OK) {
            addReplyError(c,"Error trying to load the RDB dump");
            return;
        }
        serverLog(LL_WARNING,"DB reloaded by DEBUG RELOAD");
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"loadaof")) {
        if (server.aof_state != AOF_OFF) flushAppendOnlyFile(1);
        emptyDb(-1,EMPTYDB_NO_FLAGS,NULL);
        protectClient(c);
        int ret = loadAppendOnlyFile(server.aof_filename);
        unprotectClient(c);
        if (ret != C_OK) {
            addReply(c,shared.err);
            return;
        }
        server.dirty = 0; /* Prevent AOF / replication */
        serverLog(LL_WARNING,"Append Only File loaded by DEBUG LOADAOF");
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"object") && c->argc == 3) {
        dictEntry *de;
        robj *val;
        char *strenc;

        if ((de = dictFind(c->db->dict,c->argv[2]->ptr)) == NULL) {
            addReply(c,shared.nokeyerr);
            return;
        }
        val = dictGetVal(de);
        strenc = strEncoding(val->encoding);

        char extra[138] = {0};
        if (val->encoding == OBJ_ENCODING_QUICKLIST) {
            char *nextra = extra;
            int remaining = sizeof(extra);
            quicklist *ql = val->ptr;
            /* Add number of quicklist nodes */
            int used = snprintf(nextra, remaining, " ql_nodes:%lu", ql->len);
            nextra += used;
            remaining -= used;
            /* Add average quicklist fill factor */
            double avg = (double)ql->count/ql->len;
            used = snprintf(nextra, remaining, " ql_avg_node:%.2f", avg);
            nextra += used;
            remaining -= used;
            /* Add quicklist fill level / max ziplist size */
            used = snprintf(nextra, remaining, " ql_ziplist_max:%d", ql->fill);
            nextra += used;
            remaining -= used;
            /* Add isCompressed? */
            int compressed = ql->compress != 0;
            used = snprintf(nextra, remaining, " ql_compressed:%d", compressed);
            nextra += used;
            remaining -= used;
            /* Add total uncompressed size */
            unsigned long sz = 0;
            for (quicklistNode *node = ql->head; node; node = node->next) {
                sz += node->sz;
            }
            used = snprintf(nextra, remaining, " ql_uncompressed_size:%lu", sz);
            nextra += used;
            remaining -= used;
        }

        addReplyStatusFormat(c,
            "Value at:%p refcount:%d "
            "encoding:%s serializedlength:%zu "
            "lru:%d lru_seconds_idle:%llu%s",
            (void*)val, val->refcount,
            strenc, rdbSavedObjectLen(val, c->argv[2]),
            val->lru, estimateObjectIdleTime(val)/1000, extra);
    } else if (!strcasecmp(c->argv[1]->ptr,"sdslen") && c->argc == 3) {
        dictEntry *de;
        robj *val;
        sds key;

        if ((de = dictFind(c->db->dict,c->argv[2]->ptr)) == NULL) {
            addReply(c,shared.nokeyerr);
            return;
        }
        val = dictGetVal(de);
        key = dictGetKey(de);

        if (val->type != OBJ_STRING || !sdsEncodedObject(val)) {
            addReplyError(c,"Not an sds encoded string.");
        } else {
            addReplyStatusFormat(c,
                "key_sds_len:%lld, key_sds_avail:%lld, key_zmalloc: %lld, "
                "val_sds_len:%lld, val_sds_avail:%lld, val_zmalloc: %lld",
                (long long) sdslen(key),
                (long long) sdsavail(key),
                (long long) sdsZmallocSize(key),
                (long long) sdslen(val->ptr),
                (long long) sdsavail(val->ptr),
                (long long) getStringObjectSdsUsedMemory(val));
        }
    } else if (!strcasecmp(c->argv[1]->ptr,"ziplist") && c->argc == 3) {
        robj *o;

        if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nokeyerr))
                == NULL) return;

        if (o->encoding != OBJ_ENCODING_ZIPLIST) {
            addReplyError(c,"Not an sds encoded string.");
        } else {
            ziplistRepr(o->ptr);
            addReplyStatus(c,"Ziplist structure printed on stdout");
        }
    } else if (!strcasecmp(c->argv[1]->ptr,"populate") &&
               c->argc >= 3 && c->argc <= 5) {
        long keys, j;
        robj *key, *val;
        char buf[128];

        if (getLongFromObjectOrReply(c, c->argv[2], &keys, NULL) != C_OK)
            return;
        dictExpand(c->db->dict,keys);
        for (j = 0; j < keys; j++) {
            long valsize = 0;
            snprintf(buf,sizeof(buf),"%s:%lu",
                (c->argc == 3) ? "key" : (char*)c->argv[3]->ptr, j);
            key = createStringObject(buf,strlen(buf));
            if (c->argc == 5)
                if (getLongFromObjectOrReply(c, c->argv[4], &valsize, NULL) != C_OK)
                    return;
            if (lookupKeyWrite(c->db,key) != NULL) {
                decrRefCount(key);
                continue;
            }
            snprintf(buf,sizeof(buf),"value:%lu",j);
            if (valsize==0)
                val = createStringObject(buf,strlen(buf));
            else {
                int buflen = strlen(buf);
                val = createStringObject(NULL,valsize);
                memcpy(val->ptr, buf, valsize<=buflen? valsize: buflen);
            }
            dbAdd(c->db,key,val);
            signalModifiedKey(c,c->db,key);
            decrRefCount(key);
        }
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"digest") && c->argc == 2) {
        /* DEBUG DIGEST (form without keys specified) */
        unsigned char digest[20];
        sds d = sdsempty();

        computeDatasetDigest(digest);
        for (int i = 0; i < 20; i++) d = sdscatprintf(d, "%02x",digest[i]);
        addReplyStatus(c,d);
        sdsfree(d);
    } else if (!strcasecmp(c->argv[1]->ptr,"digest-value") && c->argc >= 2) {
        /* DEBUG DIGEST-VALUE key key key ... key. */
        addReplyArrayLen(c,c->argc-2);
        for (int j = 2; j < c->argc; j++) {
            unsigned char digest[20];
            memset(digest,0,20); /* Start with a clean result */
            robj *o = lookupKeyReadWithFlags(c->db,c->argv[j],LOOKUP_NOTOUCH);
            if (o) xorObjectDigest(c->db,c->argv[j],digest,o);

            sds d = sdsempty();
            for (int i = 0; i < 20; i++) d = sdscatprintf(d, "%02x",digest[i]);
            addReplyStatus(c,d);
            sdsfree(d);
        }
    } else if (!strcasecmp(c->argv[1]->ptr,"protocol") && c->argc == 3) {
        /* DEBUG PROTOCOL [string|integer|double|bignum|null|array|set|map|
         *                 attrib|push|verbatim|true|false] */
        char *name = c->argv[2]->ptr;
        if (!strcasecmp(name,"string")) {
            addReplyBulkCString(c,"Hello World");
        } else if (!strcasecmp(name,"integer")) {
            addReplyLongLong(c,12345);
        } else if (!strcasecmp(name,"double")) {
            addReplyDouble(c,3.14159265359);
        } else if (!strcasecmp(name,"bignum")) {
            addReplyProto(c,"(1234567999999999999999999999999999999\r\n",40);
        } else if (!strcasecmp(name,"null")) {
            addReplyNull(c);
        } else if (!strcasecmp(name,"array")) {
            addReplyArrayLen(c,3);
            for (int j = 0; j < 3; j++) addReplyLongLong(c,j);
        } else if (!strcasecmp(name,"set")) {
            addReplySetLen(c,3);
            for (int j = 0; j < 3; j++) addReplyLongLong(c,j);
        } else if (!strcasecmp(name,"map")) {
            addReplyMapLen(c,3);
            for (int j = 0; j < 3; j++) {
                addReplyLongLong(c,j);
                addReplyBool(c, j == 1);
            }
        } else if (!strcasecmp(name,"attrib")) {
            addReplyAttributeLen(c,1);
            addReplyBulkCString(c,"key-popularity");
            addReplyArrayLen(c,2);
            addReplyBulkCString(c,"key:123");
            addReplyLongLong(c,90);
            /* Attributes are not real replies, so a well formed reply should
             * also have a normal reply type after the attribute. */
            addReplyBulkCString(c,"Some real reply following the attribute");
        } else if (!strcasecmp(name,"push")) {
            addReplyPushLen(c,2);
            addReplyBulkCString(c,"server-cpu-usage");
            addReplyLongLong(c,42);
            /* Push replies are not synchronous replies, so we emit also a
             * normal reply in order for blocking clients just discarding the
             * push reply, to actually consume the reply and continue. */
            addReplyBulkCString(c,"Some real reply following the push reply");
        } else if (!strcasecmp(name,"true")) {
            addReplyBool(c,1);
        } else if (!strcasecmp(name,"false")) {
            addReplyBool(c,0);
        } else if (!strcasecmp(name,"verbatim")) {
            addReplyVerbatim(c,"This is a verbatim\nstring",25,"txt");
        } else {
            addReplyError(c,"Wrong protocol type name. Please use one of the following: string|integer|double|bignum|null|array|set|map|attrib|push|verbatim|true|false");
        }
    } else if (!strcasecmp(c->argv[1]->ptr,"sleep") && c->argc == 3) {
        double dtime = strtod(c->argv[2]->ptr,NULL);
        long long utime = dtime*1000000;
        struct timespec tv;

        tv.tv_sec = utime / 1000000;
        tv.tv_nsec = (utime % 1000000) * 1000;
        nanosleep(&tv, NULL);
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"set-active-expire") &&
               c->argc == 3)
    {
        server.active_expire_enabled = atoi(c->argv[2]->ptr);
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"aof-flush-sleep") &&
               c->argc == 3)
    {
        server.aof_flush_sleep = atoi(c->argv[2]->ptr);
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"lua-always-replicate-commands") &&
               c->argc == 3)
    {
        server.lua_always_replicate_commands = atoi(c->argv[2]->ptr);
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"error") && c->argc == 3) {
        sds errstr = sdsnewlen("-",1);

        errstr = sdscatsds(errstr,c->argv[2]->ptr);
        errstr = sdsmapchars(errstr,"\n\r","  ",2); /* no newlines in errors. */
        errstr = sdscatlen(errstr,"\r\n",2);
        addReplySds(c,errstr);
    } else if (!strcasecmp(c->argv[1]->ptr,"structsize") && c->argc == 2) {
        sds sizes = sdsempty();
        sizes = sdscatprintf(sizes,"bits:%d ",(sizeof(void*) == 8)?64:32);
        sizes = sdscatprintf(sizes,"robj:%d ",(int)sizeof(robj));
        sizes = sdscatprintf(sizes,"dictentry:%d ",(int)sizeof(dictEntry));
        sizes = sdscatprintf(sizes,"sdshdr5:%d ",(int)sizeof(struct sdshdr5));
        sizes = sdscatprintf(sizes,"sdshdr8:%d ",(int)sizeof(struct sdshdr8));
        sizes = sdscatprintf(sizes,"sdshdr16:%d ",(int)sizeof(struct sdshdr16));
        sizes = sdscatprintf(sizes,"sdshdr32:%d ",(int)sizeof(struct sdshdr32));
        sizes = sdscatprintf(sizes,"sdshdr64:%d ",(int)sizeof(struct sdshdr64));
        addReplyBulkSds(c,sizes);
    } else if (!strcasecmp(c->argv[1]->ptr,"htstats") && c->argc == 3) {
        long dbid;
        sds stats = sdsempty();
        char buf[4096];

        if (getLongFromObjectOrReply(c, c->argv[2], &dbid, NULL) != C_OK) {
            sdsfree(stats);
            return;
        }
        if (dbid < 0 || dbid >= server.dbnum) {
            sdsfree(stats);
            addReplyError(c,"Out of range database");
            return;
        }

        stats = sdscatprintf(stats,"[Dictionary HT]\n");
        dictGetStats(buf,sizeof(buf),server.db[dbid].dict);
        stats = sdscat(stats,buf);

        stats = sdscatprintf(stats,"[Expires HT]\n");
        dictGetStats(buf,sizeof(buf),server.db[dbid].expires);
        stats = sdscat(stats,buf);

        addReplyVerbatim(c,stats,sdslen(stats),"txt");
        sdsfree(stats);
    } else if (!strcasecmp(c->argv[1]->ptr,"htstats-key") && c->argc == 3) {
        robj *o;
        dict *ht = NULL;

        if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nokeyerr))
                == NULL) return;

        /* Get the hash table reference from the object, if possible. */
        switch (o->encoding) {
        case OBJ_ENCODING_SKIPLIST:
            {
                zset *zs = o->ptr;
                ht = zs->dict;
            }
            break;
        case OBJ_ENCODING_HT:
            ht = o->ptr;
            break;
        }

        if (ht == NULL) {
            addReplyError(c,"The value stored at the specified key is not "
                            "represented using an hash table");
        } else {
            char buf[4096];
            dictGetStats(buf,sizeof(buf),ht);
            addReplyVerbatim(c,buf,strlen(buf),"txt");
        }
    } else if (!strcasecmp(c->argv[1]->ptr,"change-repl-id") && c->argc == 2) {
        serverLog(LL_WARNING,"Changing replication IDs after receiving DEBUG change-repl-id");
        changeReplicationId();
        clearReplicationId2();
        addReply(c,shared.ok);
    } else if (!strcasecmp(c->argv[1]->ptr,"stringmatch-test") && c->argc == 2)
    {
        stringmatchlen_fuzz_test();
        addReplyStatus(c,"Apparently Redis did not crash: test passed");
#ifdef USE_JEMALLOC
    } else if(!strcasecmp(c->argv[1]->ptr,"mallctl") && c->argc >= 3) {
        mallctl_int(c, c->argv+2, c->argc-2);
        return;
    } else if(!strcasecmp(c->argv[1]->ptr,"mallctl-str") && c->argc >= 3) {
        mallctl_string(c, c->argv+2, c->argc-2);
        return;
#endif
    } else {
        addReplySubcommandSyntaxError(c);
        return;
    }
}

/* =========================== Crash handling  ============================== */

void _serverAssert(const char *estr, const char *file, int line) {
    bugReportStart();
    serverLog(LL_WARNING,"=== ASSERTION FAILED ===");
    serverLog(LL_WARNING,"==> %s:%d '%s' is not true",file,line,estr);
#ifdef HAVE_BACKTRACE
    server.assert_failed = estr;
    server.assert_file = file;
    server.assert_line = line;
    serverLog(LL_WARNING,"(forcing SIGSEGV to print the bug report.)");
#endif
    *((char*)-1) = 'x';
}

void _serverAssertPrintClientInfo(const client *c) {
    int j;
    char conninfo[CONN_INFO_LEN];

    bugReportStart();
    serverLog(LL_WARNING,"=== ASSERTION FAILED CLIENT CONTEXT ===");
    serverLog(LL_WARNING,"client->flags = %llu", (unsigned long long) c->flags);
    serverLog(LL_WARNING,"client->conn = %s", connGetInfo(c->conn, conninfo, sizeof(conninfo)));
    serverLog(LL_WARNING,"client->argc = %d", c->argc);
    for (j=0; j < c->argc; j++) {
        char buf[128];
        char *arg;

        if (c->argv[j]->type == OBJ_STRING && sdsEncodedObject(c->argv[j])) {
            arg = (char*) c->argv[j]->ptr;
        } else {
            snprintf(buf,sizeof(buf),"Object type: %u, encoding: %u",
                c->argv[j]->type, c->argv[j]->encoding);
            arg = buf;
        }
        serverLog(LL_WARNING,"client->argv[%d] = \"%s\" (refcount: %d)",
            j, arg, c->argv[j]->refcount);
    }
}

void serverLogObjectDebugInfo(const robj *o) {
    serverLog(LL_WARNING,"Object type: %d", o->type);
    serverLog(LL_WARNING,"Object encoding: %d", o->encoding);
    serverLog(LL_WARNING,"Object refcount: %d", o->refcount);
    if (o->type == OBJ_STRING && sdsEncodedObject(o)) {
        serverLog(LL_WARNING,"Object raw string len: %zu", sdslen(o->ptr));
        if (sdslen(o->ptr) < 4096) {
            sds repr = sdscatrepr(sdsempty(),o->ptr,sdslen(o->ptr));
            serverLog(LL_WARNING,"Object raw string content: %s", repr);
            sdsfree(repr);
        }
    } else if (o->type == OBJ_LIST) {
        serverLog(LL_WARNING,"List length: %d", (int) listTypeLength(o));
    } else if (o->type == OBJ_SET) {
        serverLog(LL_WARNING,"Set size: %d", (int) setTypeSize(o));
    } else if (o->type == OBJ_HASH) {
        serverLog(LL_WARNING,"Hash size: %d", (int) hashTypeLength(o));
    } else if (o->type == OBJ_ZSET) {
        serverLog(LL_WARNING,"Sorted set size: %d", (int) zsetLength(o));
        if (o->encoding == OBJ_ENCODING_SKIPLIST)
            serverLog(LL_WARNING,"Skiplist level: %d", (int) ((const zset*)o->ptr)->zsl->level);
    } else if (o->type == OBJ_STREAM) {
        serverLog(LL_WARNING,"Stream size: %d", (int) streamLength(o));
    }
}

void _serverAssertPrintObject(const robj *o) {
    bugReportStart();
    serverLog(LL_WARNING,"=== ASSERTION FAILED OBJECT CONTEXT ===");
    serverLogObjectDebugInfo(o);
}

void _serverAssertWithInfo(const client *c, const robj *o, const char *estr, const char *file, int line) {
    if (c) _serverAssertPrintClientInfo(c);
    if (o) _serverAssertPrintObject(o);
    _serverAssert(estr,file,line);
}

void _serverPanic(const char *file, int line, const char *msg, ...) {
    va_list ap;
    va_start(ap,msg);
    char fmtmsg[256];
    vsnprintf(fmtmsg,sizeof(fmtmsg),msg,ap);
    va_end(ap);

    bugReportStart();
    serverLog(LL_WARNING,"------------------------------------------------");
    serverLog(LL_WARNING,"!!! Software Failure. Press left mouse button to continue");
    serverLog(LL_WARNING,"Guru Meditation: %s #%s:%d",fmtmsg,file,line);
#ifdef HAVE_BACKTRACE
    serverLog(LL_WARNING,"(forcing SIGSEGV in order to print the stack trace)");
#endif
    serverLog(LL_WARNING,"------------------------------------------------");
    *((char*)-1) = 'x';
}

void bugReportStart(void) {
    if (server.bug_report_start == 0) {
        serverLogRaw(LL_WARNING|LL_RAW,
        "\n\n=== REDIS BUG REPORT START: Cut & paste starting from here ===\n");
        server.bug_report_start = 1;
    }
}

#ifdef HAVE_BACKTRACE
static void *getMcontextEip(ucontext_t *uc) {
#if defined(__APPLE__) && !defined(MAC_OS_X_VERSION_10_6)
    /* OSX < 10.6 */
    #if defined(__x86_64__)
    return (void*) uc->uc_mcontext->__ss.__rip;
    #elif defined(__i386__)
    return (void*) uc->uc_mcontext->__ss.__eip;
    #else
    return (void*) uc->uc_mcontext->__ss.__srr0;
    #endif
#elif defined(__APPLE__) && defined(MAC_OS_X_VERSION_10_6)
    /* OSX >= 10.6 */
    #if defined(_STRUCT_X86_THREAD_STATE64) && !defined(__i386__)
    return (void*) uc->uc_mcontext->__ss.__rip;
    #elif defined(__i386__)
    return (void*) uc->uc_mcontext->__ss.__eip;
    #else
    /* OSX ARM64 */
    return (void*) arm_thread_state64_get_pc(uc->uc_mcontext->__ss);
    #endif
#elif defined(__linux__)
    /* Linux */
    #if defined(__i386__) || defined(__ILP32__)
    return (void*) uc->uc_mcontext.gregs[14]; /* Linux 32 */
    #elif defined(__X86_64__) || defined(__x86_64__)
    return (void*) uc->uc_mcontext.gregs[16]; /* Linux 64 */
    #elif defined(__ia64__) /* Linux IA64 */
    return (void*) uc->uc_mcontext.sc_ip;
    #elif defined(__arm__) /* Linux ARM */
    return (void*) uc->uc_mcontext.arm_pc;
    #elif defined(__aarch64__) /* Linux AArch64 */
    return (void*) uc->uc_mcontext.pc;
    #endif
#elif defined(__FreeBSD__)
    /* FreeBSD */
    #if defined(__i386__)
    return (void*) uc->uc_mcontext.mc_eip;
    #elif defined(__x86_64__)
    return (void*) uc->uc_mcontext.mc_rip;
    #endif
#elif defined(__OpenBSD__)
    /* OpenBSD */
    #if defined(__i386__)
    return (void*) uc->sc_eip;
    #elif defined(__x86_64__)
    return (void*) uc->sc_rip;
    #endif
#elif defined(__DragonFly__)
    return (void*) uc->uc_mcontext.mc_rip;
#else
    return NULL;
#endif
}

void logStackContent(void **sp) {
    int i;
    for (i = 15; i >= 0; i--) {
        unsigned long addr = (unsigned long) sp+i;
        unsigned long val = (unsigned long) sp[i];

        if (sizeof(long) == 4)
            serverLog(LL_WARNING, "(%08lx) -> %08lx", addr, val);
        else
            serverLog(LL_WARNING, "(%016lx) -> %016lx", addr, val);
    }
}

void logRegisters(ucontext_t *uc) {
    serverLog(LL_WARNING|LL_RAW, "\n------ REGISTERS ------\n");

/* OSX */
#if defined(__APPLE__) && defined(MAC_OS_X_VERSION_10_6)
  /* OSX AMD64 */
    #if defined(_STRUCT_X86_THREAD_STATE64) && !defined(__i386__)
    serverLog(LL_WARNING,
    "\n"
    "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
    "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
    "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
    "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
    "RIP:%016lx EFL:%016lx\nCS :%016lx FS:%016lx  GS:%016lx",
        (unsigned long) uc->uc_mcontext->__ss.__rax,
        (unsigned long) uc->uc_mcontext->__ss.__rbx,
        (unsigned long) uc->uc_mcontext->__ss.__rcx,
        (unsigned long) uc->uc_mcontext->__ss.__rdx,
        (unsigned long) uc->uc_mcontext->__ss.__rdi,
        (unsigned long) uc->uc_mcontext->__ss.__rsi,
        (unsigned long) uc->uc_mcontext->__ss.__rbp,
        (unsigned long) uc->uc_mcontext->__ss.__rsp,
        (unsigned long) uc->uc_mcontext->__ss.__r8,
        (unsigned long) uc->uc_mcontext->__ss.__r9,
        (unsigned long) uc->uc_mcontext->__ss.__r10,
        (unsigned long) uc->uc_mcontext->__ss.__r11,
        (unsigned long) uc->uc_mcontext->__ss.__r12,
        (unsigned long) uc->uc_mcontext->__ss.__r13,
        (unsigned long) uc->uc_mcontext->__ss.__r14,
        (unsigned long) uc->uc_mcontext->__ss.__r15,
        (unsigned long) uc->uc_mcontext->__ss.__rip,
        (unsigned long) uc->uc_mcontext->__ss.__rflags,
        (unsigned long) uc->uc_mcontext->__ss.__cs,
        (unsigned long) uc->uc_mcontext->__ss.__fs,
        (unsigned long) uc->uc_mcontext->__ss.__gs
    );
    logStackContent((void**)uc->uc_mcontext->__ss.__rsp);
    #elif defined(__i386__)
    /* OSX x86 */
    serverLog(LL_WARNING,
    "\n"
    "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
    "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
    "SS:%08lx  EFL:%08lx EIP:%08lx CS :%08lx\n"
    "DS:%08lx  ES:%08lx  FS :%08lx GS :%08lx",
        (unsigned long) uc->uc_mcontext->__ss.__eax,
        (unsigned long) uc->uc_mcontext->__ss.__ebx,
        (unsigned long) uc->uc_mcontext->__ss.__ecx,
        (unsigned long) uc->uc_mcontext->__ss.__edx,
        (unsigned long) uc->uc_mcontext->__ss.__edi,
        (unsigned long) uc->uc_mcontext->__ss.__esi,
        (unsigned long) uc->uc_mcontext->__ss.__ebp,
        (unsigned long) uc->uc_mcontext->__ss.__esp,
        (unsigned long) uc->uc_mcontext->__ss.__ss,
        (unsigned long) uc->uc_mcontext->__ss.__eflags,
        (unsigned long) uc->uc_mcontext->__ss.__eip,
        (unsigned long) uc->uc_mcontext->__ss.__cs,
        (unsigned long) uc->uc_mcontext->__ss.__ds,
        (unsigned long) uc->uc_mcontext->__ss.__es,
        (unsigned long) uc->uc_mcontext->__ss.__fs,
        (unsigned long) uc->uc_mcontext->__ss.__gs
    );
    logStackContent((void**)uc->uc_mcontext->__ss.__esp);
    #else
    /* OSX ARM64 */
    serverLog(LL_WARNING,
    "\n"
    "x0:%016lx x1:%016lx x2:%016lx x3:%016lx\n"
    "x4:%016lx x5:%016lx x6:%016lx x7:%016lx\n"
    "x8:%016lx x9:%016lx x10:%016lx x11:%016lx\n"
    "x12:%016lx x13:%016lx x14:%016lx x15:%016lx\n"
    "x16:%016lx x17:%016lx x18:%016lx x19:%016lx\n"
    "x20:%016lx x21:%016lx x22:%016lx x23:%016lx\n"
    "x24:%016lx x25:%016lx x26:%016lx x27:%016lx\n"
    "x28:%016lx fp:%016lx lr:%016lx\n"
    "sp:%016lx pc:%016lx cpsr:%08lx\n",
        (unsigned long) uc->uc_mcontext->__ss.__x[0],
        (unsigned long) uc->uc_mcontext->__ss.__x[1],
        (unsigned long) uc->uc_mcontext->__ss.__x[2],
        (unsigned long) uc->uc_mcontext->__ss.__x[3],
        (unsigned long) uc->uc_mcontext->__ss.__x[4],
        (unsigned long) uc->uc_mcontext->__ss.__x[5],
        (unsigned long) uc->uc_mcontext->__ss.__x[6],
        (unsigned long) uc->uc_mcontext->__ss.__x[7],
        (unsigned long) uc->uc_mcontext->__ss.__x[8],
        (unsigned long) uc->uc_mcontext->__ss.__x[9],
        (unsigned long) uc->uc_mcontext->__ss.__x[10],
        (unsigned long) uc->uc_mcontext->__ss.__x[11],
        (unsigned long) uc->uc_mcontext->__ss.__x[12],
        (unsigned long) uc->uc_mcontext->__ss.__x[13],
        (unsigned long) uc->uc_mcontext->__ss.__x[14],
        (unsigned long) uc->uc_mcontext->__ss.__x[15],
        (unsigned long) uc->uc_mcontext->__ss.__x[16],
        (unsigned long) uc->uc_mcontext->__ss.__x[17],
        (unsigned long) uc->uc_mcontext->__ss.__x[18],
        (unsigned long) uc->uc_mcontext->__ss.__x[19],
        (unsigned long) uc->uc_mcontext->__ss.__x[20],
        (unsigned long) uc->uc_mcontext->__ss.__x[21],
        (unsigned long) uc->uc_mcontext->__ss.__x[22],
        (unsigned long) uc->uc_mcontext->__ss.__x[23],
        (unsigned long) uc->uc_mcontext->__ss.__x[24],
        (unsigned long) uc->uc_mcontext->__ss.__x[25],
        (unsigned long) uc->uc_mcontext->__ss.__x[26],
        (unsigned long) uc->uc_mcontext->__ss.__x[27],
        (unsigned long) uc->uc_mcontext->__ss.__x[28],
        (unsigned long) arm_thread_state64_get_fp(uc->uc_mcontext->__ss),
        (unsigned long) arm_thread_state64_get_lr(uc->uc_mcontext->__ss),
        (unsigned long) arm_thread_state64_get_sp(uc->uc_mcontext->__ss),
        (unsigned long) arm_thread_state64_get_pc(uc->uc_mcontext->__ss),
        (unsigned long) uc->uc_mcontext->__ss.__cpsr
    );
    logStackContent((void**) arm_thread_state64_get_sp(uc->uc_mcontext->__ss));
    #endif
/* Linux */
#elif defined(__linux__)
    /* Linux x86 */
    #if defined(__i386__) || defined(__ILP32__)
    serverLog(LL_WARNING,
    "\n"
    "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
    "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
    "SS :%08lx EFL:%08lx EIP:%08lx CS:%08lx\n"
    "DS :%08lx ES :%08lx FS :%08lx GS:%08lx",
        (unsigned long) uc->uc_mcontext.gregs[11],
        (unsigned long) uc->uc_mcontext.gregs[8],
        (unsigned long) uc->uc_mcontext.gregs[10],
        (unsigned long) uc->uc_mcontext.gregs[9],
        (unsigned long) uc->uc_mcontext.gregs[4],
        (unsigned long) uc->uc_mcontext.gregs[5],
        (unsigned long) uc->uc_mcontext.gregs[6],
        (unsigned long) uc->uc_mcontext.gregs[7],
        (unsigned long) uc->uc_mcontext.gregs[18],
        (unsigned long) uc->uc_mcontext.gregs[17],
        (unsigned long) uc->uc_mcontext.gregs[14],
        (unsigned long) uc->uc_mcontext.gregs[15],
        (unsigned long) uc->uc_mcontext.gregs[3],
        (unsigned long) uc->uc_mcontext.gregs[2],
        (unsigned long) uc->uc_mcontext.gregs[1],
        (unsigned long) uc->uc_mcontext.gregs[0]
    );
    logStackContent((void**)uc->uc_mcontext.gregs[7]);
    #elif defined(__X86_64__) || defined(__x86_64__)
    /* Linux AMD64 */
    serverLog(LL_WARNING,
    "\n"
    "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
    "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
    "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
    "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
    "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
        (unsigned long) uc->uc_mcontext.gregs[13],
        (unsigned long) uc->uc_mcontext.gregs[11],
        (unsigned long) uc->uc_mcontext.gregs[14],
        (unsigned long) uc->uc_mcontext.gregs[12],
        (unsigned long) uc->uc_mcontext.gregs[8],
        (unsigned long) uc->uc_mcontext.gregs[9],
        (unsigned long) uc->uc_mcontext.gregs[10],
        (unsigned long) uc->uc_mcontext.gregs[15],
        (unsigned long) uc->uc_mcontext.gregs[0],
        (unsigned long) uc->uc_mcontext.gregs[1],
        (unsigned long) uc->uc_mcontext.gregs[2],
        (unsigned long) uc->uc_mcontext.gregs[3],
        (unsigned long) uc->uc_mcontext.gregs[4],
        (unsigned long) uc->uc_mcontext.gregs[5],
        (unsigned long) uc->uc_mcontext.gregs[6],
        (unsigned long) uc->uc_mcontext.gregs[7],
        (unsigned long) uc->uc_mcontext.gregs[16],
        (unsigned long) uc->uc_mcontext.gregs[17],
        (unsigned long) uc->uc_mcontext.gregs[18]
    );
    logStackContent((void**)uc->uc_mcontext.gregs[15]);
    #elif defined(__aarch64__) /* Linux AArch64 */
    serverLog(LL_WARNING,
	      "\n"
	      "X18:%016lx X19:%016lx\nX20:%016lx X21:%016lx\n"
	      "X22:%016lx X23:%016lx\nX24:%016lx X25:%016lx\n"
	      "X26:%016lx X27:%016lx\nX28:%016lx X29:%016lx\n"
	      "X30:%016lx\n"
	      "pc:%016lx sp:%016lx\npstate:%016lx fault_address:%016lx\n",
	      (unsigned long) uc->uc_mcontext.regs[18],
	      (unsigned long) uc->uc_mcontext.regs[19],
	      (unsigned long) uc->uc_mcontext.regs[20],
	      (unsigned long) uc->uc_mcontext.regs[21],
	      (unsigned long) uc->uc_mcontext.regs[22],
	      (unsigned long) uc->uc_mcontext.regs[23],
	      (unsigned long) uc->uc_mcontext.regs[24],
	      (unsigned long) uc->uc_mcontext.regs[25],
	      (unsigned long) uc->uc_mcontext.regs[26],
	      (unsigned long) uc->uc_mcontext.regs[27],
	      (unsigned long) uc->uc_mcontext.regs[28],
	      (unsigned long) uc->uc_mcontext.regs[29],
	      (unsigned long) uc->uc_mcontext.regs[30],
	      (unsigned long) uc->uc_mcontext.pc,
	      (unsigned long) uc->uc_mcontext.sp,
	      (unsigned long) uc->uc_mcontext.pstate,
	      (unsigned long) uc->uc_mcontext.fault_address
		      );
	      logStackContent((void**)uc->uc_mcontext.sp);
    #elif defined(__arm__) /* Linux ARM */
    serverLog(LL_WARNING,
	      "\n"
	      "R10:%016lx R9 :%016lx\nR8 :%016lx R7 :%016lx\n"
	      "R6 :%016lx R5 :%016lx\nR4 :%016lx R3 :%016lx\n"
	      "R2 :%016lx R1 :%016lx\nR0 :%016lx EC :%016lx\n"
	      "fp: %016lx ip:%016lx\n",
	      "pc:%016lx sp:%016lx\ncpsr:%016lx fault_address:%016lx\n",
	      (unsigned long) uc->uc_mcontext.arm_r10,
	      (unsigned long) uc->uc_mcontext.arm_r9,
	      (unsigned long) uc->uc_mcontext.arm_r8,
	      (unsigned long) uc->uc_mcontext.arm_r7,
	      (unsigned long) uc->uc_mcontext.arm_r6,
	      (unsigned long) uc->uc_mcontext.arm_r5,
	      (unsigned long) uc->uc_mcontext.arm_r4,
	      (unsigned long) uc->uc_mcontext.arm_r3,
	      (unsigned long) uc->uc_mcontext.arm_r2,
	      (unsigned long) uc->uc_mcontext.arm_r1,
	      (unsigned long) uc->uc_mcontext.arm_r0,
	      (unsigned long) uc->uc_mcontext.error_code,
	      (unsigned long) uc->uc_mcontext.arm_fp,
	      (unsigned long) uc->uc_mcontext.arm_ip,
	      (unsigned long) uc->uc_mcontext.arm_pc,
	      (unsigned long) uc->uc_mcontext.arm_sp,
	      (unsigned long) uc->uc_mcontext.arm_cpsr,
	      (unsigned long) uc->uc_mcontext.fault_address
		      );
	      logStackContent((void**)uc->uc_mcontext.arm_sp);
    #endif
#elif defined(__FreeBSD__)
    #if defined(__x86_64__)
    serverLog(LL_WARNING,
    "\n"
    "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
    "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
    "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
    "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
    "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
        (unsigned long) uc->uc_mcontext.mc_rax,
        (unsigned long) uc->uc_mcontext.mc_rbx,
        (unsigned long) uc->uc_mcontext.mc_rcx,
        (unsigned long) uc->uc_mcontext.mc_rdx,
        (unsigned long) uc->uc_mcontext.mc_rdi,
        (unsigned long) uc->uc_mcontext.mc_rsi,
        (unsigned long) uc->uc_mcontext.mc_rbp,
        (unsigned long) uc->uc_mcontext.mc_rsp,
        (unsigned long) uc->uc_mcontext.mc_r8,
        (unsigned long) uc->uc_mcontext.mc_r9,
        (unsigned long) uc->uc_mcontext.mc_r10,
        (unsigned long) uc->uc_mcontext.mc_r11,
        (unsigned long) uc->uc_mcontext.mc_r12,
        (unsigned long) uc->uc_mcontext.mc_r13,
        (unsigned long) uc->uc_mcontext.mc_r14,
        (unsigned long) uc->uc_mcontext.mc_r15,
        (unsigned long) uc->uc_mcontext.mc_rip,
        (unsigned long) uc->uc_mcontext.mc_rflags,
        (unsigned long) uc->uc_mcontext.mc_cs
    );
    logStackContent((void**)uc->uc_mcontext.mc_rsp);
    #elif defined(__i386__)
    serverLog(LL_WARNING,
    "\n"
    "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
    "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
    "SS :%08lx EFL:%08lx EIP:%08lx CS:%08lx\n"
    "DS :%08lx ES :%08lx FS :%08lx GS:%08lx",
        (unsigned long) uc->uc_mcontext.mc_eax,
        (unsigned long) uc->uc_mcontext.mc_ebx,
        (unsigned long) uc->uc_mcontext.mc_ebx,
        (unsigned long) uc->uc_mcontext.mc_edx,
        (unsigned long) uc->uc_mcontext.mc_edi,
        (unsigned long) uc->uc_mcontext.mc_esi,
        (unsigned long) uc->uc_mcontext.mc_ebp,
        (unsigned long) uc->uc_mcontext.mc_esp,
        (unsigned long) uc->uc_mcontext.mc_ss,
        (unsigned long) uc->uc_mcontext.mc_eflags,
        (unsigned long) uc->uc_mcontext.mc_eip,
        (unsigned long) uc->uc_mcontext.mc_cs,
        (unsigned long) uc->uc_mcontext.mc_es,
        (unsigned long) uc->uc_mcontext.mc_fs,
        (unsigned long) uc->uc_mcontext.mc_gs
    );
    logStackContent((void**)uc->uc_mcontext.mc_esp);
    #endif
#elif defined(__OpenBSD__)
    #if defined(__x86_64__)
    serverLog(LL_WARNING,
    "\n"
    "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
    "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
    "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
    "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
    "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
        (unsigned long) uc->sc_rax,
        (unsigned long) uc->sc_rbx,
        (unsigned long) uc->sc_rcx,
        (unsigned long) uc->sc_rdx,
        (unsigned long) uc->sc_rdi,
        (unsigned long) uc->sc_rsi,
        (unsigned long) uc->sc_rbp,
        (unsigned long) uc->sc_rsp,
        (unsigned long) uc->sc_r8,
        (unsigned long) uc->sc_r9,
        (unsigned long) uc->sc_r10,
        (unsigned long) uc->sc_r11,
        (unsigned long) uc->sc_r12,
        (unsigned long) uc->sc_r13,
        (unsigned long) uc->sc_r14,
        (unsigned long) uc->sc_r15,
        (unsigned long) uc->sc_rip,
        (unsigned long) uc->sc_rflags,
        (unsigned long) uc->sc_cs
    );
    logStackContent((void**)uc->sc_rsp);
    #elif defined(__i386__)
    serverLog(LL_WARNING,
    "\n"
    "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
    "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
    "SS :%08lx EFL:%08lx EIP:%08lx CS:%08lx\n"
    "DS :%08lx ES :%08lx FS :%08lx GS:%08lx",
        (unsigned long) uc->sc_eax,
        (unsigned long) uc->sc_ebx,
        (unsigned long) uc->sc_ebx,
        (unsigned long) uc->sc_edx,
        (unsigned long) uc->sc_edi,
        (unsigned long) uc->sc_esi,
        (unsigned long) uc->sc_ebp,
        (unsigned long) uc->sc_esp,
        (unsigned long) uc->sc_ss,
        (unsigned long) uc->sc_eflags,
        (unsigned long) uc->sc_eip,
        (unsigned long) uc->sc_cs,
        (unsigned long) uc->sc_es,
        (unsigned long) uc->sc_fs,
        (unsigned long) uc->sc_gs
    );
    logStackContent((void**)uc->sc_esp);
    #endif
#elif defined(__DragonFly__)
    serverLog(LL_WARNING,
    "\n"
    "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
    "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
    "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
    "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
    "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
        (unsigned long) uc->uc_mcontext.mc_rax,
        (unsigned long) uc->uc_mcontext.mc_rbx,
        (unsigned long) uc->uc_mcontext.mc_rcx,
        (unsigned long) uc->uc_mcontext.mc_rdx,
        (unsigned long) uc->uc_mcontext.mc_rdi,
        (unsigned long) uc->uc_mcontext.mc_rsi,
        (unsigned long) uc->uc_mcontext.mc_rbp,
        (unsigned long) uc->uc_mcontext.mc_rsp,
        (unsigned long) uc->uc_mcontext.mc_r8,
        (unsigned long) uc->uc_mcontext.mc_r9,
        (unsigned long) uc->uc_mcontext.mc_r10,
        (unsigned long) uc->uc_mcontext.mc_r11,
        (unsigned long) uc->uc_mcontext.mc_r12,
        (unsigned long) uc->uc_mcontext.mc_r13,
        (unsigned long) uc->uc_mcontext.mc_r14,
        (unsigned long) uc->uc_mcontext.mc_r15,
        (unsigned long) uc->uc_mcontext.mc_rip,
        (unsigned long) uc->uc_mcontext.mc_rflags,
        (unsigned long) uc->uc_mcontext.mc_cs
    );
    logStackContent((void**)uc->uc_mcontext.mc_rsp);
#else
    serverLog(LL_WARNING,
        "  Dumping of registers not supported for this OS/arch");
#endif
}

/* Return a file descriptor to write directly to the Redis log with the
 * write(2) syscall, that can be used in critical sections of the code
 * where the rest of Redis can't be trusted (for example during the memory
 * test) or when an API call requires a raw fd.
 *
 * Close it with closeDirectLogFiledes(). */
int openDirectLogFiledes(void) {
    int log_to_stdout = server.logfile[0] == '\0';
    int fd = log_to_stdout ?
        STDOUT_FILENO :
        open(server.logfile, O_APPEND|O_CREAT|O_WRONLY, 0644);
    return fd;
}

/* Used to close what closeDirectLogFiledes() returns. */
void closeDirectLogFiledes(int fd) {
    int log_to_stdout = server.logfile[0] == '\0';
    if (!log_to_stdout) close(fd);
}

/* Logs the stack trace using the backtrace() call. This function is designed
 * to be called from signal handlers safely. */
void logStackTrace(ucontext_t *uc) {
    void *trace[101];
    int trace_size = 0, fd = openDirectLogFiledes();

    if (fd == -1) return; /* If we can't log there is anything to do. */

    /* Generate the stack trace */
    trace_size = backtrace(trace+1, 100);

    if (getMcontextEip(uc) != NULL) {
        char *msg1 = "EIP:\n";
        char *msg2 = "\nBacktrace:\n";
        if (write(fd,msg1,strlen(msg1)) == -1) {/* Avoid warning. */};
        trace[0] = getMcontextEip(uc);
        backtrace_symbols_fd(trace, 1, fd);
        if (write(fd,msg2,strlen(msg2)) == -1) {/* Avoid warning. */};
    }

    /* Write symbols to log file */
    backtrace_symbols_fd(trace+1, trace_size, fd);

    /* Cleanup */
    closeDirectLogFiledes(fd);
}

/* Log information about the "current" client, that is, the client that is
 * currently being served by Redis. May be NULL if Redis is not serving a
 * client right now. */
void logCurrentClient(void) {
    if (server.current_client == NULL) return;

    client *cc = server.current_client;
    sds client;
    int j;

    serverLogRaw(LL_WARNING|LL_RAW, "\n------ CURRENT CLIENT INFO ------\n");
    client = catClientInfoString(sdsempty(),cc);
    serverLog(LL_WARNING|LL_RAW,"%s\n", client);
    sdsfree(client);
    for (j = 0; j < cc->argc; j++) {
        robj *decoded;

        decoded = getDecodedObject(cc->argv[j]);
        serverLog(LL_WARNING|LL_RAW,"argv[%d]: '%s'\n", j,
            (char*)decoded->ptr);
        decrRefCount(decoded);
    }
    /* Check if the first argument, usually a key, is found inside the
     * selected DB, and if so print info about the associated object. */
    if (cc->argc >= 1) {
        robj *val, *key;
        dictEntry *de;

        key = getDecodedObject(cc->argv[1]);
        de = dictFind(cc->db->dict, key->ptr);
        if (de) {
            val = dictGetVal(de);
            serverLog(LL_WARNING,"key '%s' found in DB containing the following object:", (char*)key->ptr);
            serverLogObjectDebugInfo(val);
        }
        decrRefCount(key);
    }
}

#if defined(HAVE_PROC_MAPS)

#define MEMTEST_MAX_REGIONS 128

/* A non destructive memory test executed during segfauls. */
int memtest_test_linux_anonymous_maps(void) {
    FILE *fp;
    char line[1024];
    char logbuf[1024];
    size_t start_addr, end_addr, size;
    size_t start_vect[MEMTEST_MAX_REGIONS];
    size_t size_vect[MEMTEST_MAX_REGIONS];
    int regions = 0, j;

    int fd = openDirectLogFiledes();
    if (!fd) return 0;

    fp = fopen("/proc/self/maps","r");
    if (!fp) return 0;
    while(fgets(line,sizeof(line),fp) != NULL) {
        char *start, *end, *p = line;

        start = p;
        p = strchr(p,'-');
        if (!p) continue;
        *p++ = '\0';
        end = p;
        p = strchr(p,' ');
        if (!p) continue;
        *p++ = '\0';
        if (strstr(p,"stack") ||
            strstr(p,"vdso") ||
            strstr(p,"vsyscall")) continue;
        if (!strstr(p,"00:00")) continue;
        if (!strstr(p,"rw")) continue;

        start_addr = strtoul(start,NULL,16);
        end_addr = strtoul(end,NULL,16);
        size = end_addr-start_addr;

        start_vect[regions] = start_addr;
        size_vect[regions] = size;
        snprintf(logbuf,sizeof(logbuf),
            "*** Preparing to test memory region %lx (%lu bytes)\n",
                (unsigned long) start_vect[regions],
                (unsigned long) size_vect[regions]);
        if (write(fd,logbuf,strlen(logbuf)) == -1) { /* Nothing to do. */ }
        regions++;
    }

    int errors = 0;
    for (j = 0; j < regions; j++) {
        if (write(fd,".",1) == -1) { /* Nothing to do. */ }
        errors += memtest_preserving_test((void*)start_vect[j],size_vect[j],1);
        if (write(fd, errors ? "E" : "O",1) == -1) { /* Nothing to do. */ }
    }
    if (write(fd,"\n",1) == -1) { /* Nothing to do. */ }

    /* NOTE: It is very important to close the file descriptor only now
     * because closing it before may result into unmapping of some memory
     * region that we are testing. */
    fclose(fp);
    closeDirectLogFiledes(fd);
    return errors;
}
#endif

/* Scans the (assumed) x86 code starting at addr, for a max of `len`
 * bytes, searching for E8 (callq) opcodes, and dumping the symbols
 * and the call offset if they appear to be valid. */
void dumpX86Calls(void *addr, size_t len) {
    size_t j;
    unsigned char *p = addr;
    Dl_info info;
    /* Hash table to best-effort avoid printing the same symbol
     * multiple times. */
    unsigned long ht[256] = {0};

    if (len < 5) return;
    for (j = 0; j < len-4; j++) {
        if (p[j] != 0xE8) continue; /* Not an E8 CALL opcode. */
        unsigned long target = (unsigned long)addr+j+5;
        target += *((int32_t*)(p+j+1));
        if (dladdr((void*)target, &info) != 0 && info.dli_sname != NULL) {
            if (ht[target&0xff] != target) {
                printf("Function at 0x%lx is %s\n",target,info.dli_sname);
                ht[target&0xff] = target;
            }
            j += 4; /* Skip the 32 bit immediate. */
        }
    }
}

void sigsegvHandler(int sig, siginfo_t *info, void *secret) {
    ucontext_t *uc = (ucontext_t*) secret;
    void *eip = getMcontextEip(uc);
    sds infostring, clients;
    struct sigaction act;
    UNUSED(info);

    bugReportStart();
    serverLog(LL_WARNING,
        "Redis %s crashed by signal: %d", REDIS_VERSION, sig);
    if (eip != NULL) {
        serverLog(LL_WARNING,
        "Crashed running the instruction at: %p", eip);
    }
    if (sig == SIGSEGV || sig == SIGBUS) {
        serverLog(LL_WARNING,
        "Accessing address: %p", (void*)info->si_addr);
    }
    serverLog(LL_WARNING,
        "Failed assertion: %s (%s:%d)", server.assert_failed,
                        server.assert_file, server.assert_line);

    /* Log the stack trace */
    serverLogRaw(LL_WARNING|LL_RAW, "\n------ STACK TRACE ------\n");
    logStackTrace(uc);

    /* Log INFO and CLIENT LIST */
    serverLogRaw(LL_WARNING|LL_RAW, "\n------ INFO OUTPUT ------\n");
    infostring = genRedisInfoString("all");
    serverLogRaw(LL_WARNING|LL_RAW, infostring);
    serverLogRaw(LL_WARNING|LL_RAW, "\n------ CLIENT LIST OUTPUT ------\n");
    clients = getAllClientsInfoString(-1);
    serverLogRaw(LL_WARNING|LL_RAW, clients);
    sdsfree(infostring);
    sdsfree(clients);

    /* Log the current client */
    logCurrentClient();

    /* Log dump of processor registers */
    logRegisters(uc);

    /* Log Modules INFO */
    serverLogRaw(LL_WARNING|LL_RAW, "\n------ MODULES INFO OUTPUT ------\n");
    infostring = modulesCollectInfo(sdsempty(), NULL, 1, 0);
    serverLogRaw(LL_WARNING|LL_RAW, infostring);
    sdsfree(infostring);

#if defined(HAVE_PROC_MAPS)
    /* Test memory */
    serverLogRaw(LL_WARNING|LL_RAW, "\n------ FAST MEMORY TEST ------\n");
    bioKillThreads();
    if (memtest_test_linux_anonymous_maps()) {
        serverLogRaw(LL_WARNING|LL_RAW,
            "!!! MEMORY ERROR DETECTED! Check your memory ASAP !!!\n");
    } else {
        serverLogRaw(LL_WARNING|LL_RAW,
            "Fast memory test PASSED, however your memory can still be broken. Please run a memory test for several hours if possible.\n");
    }
#endif

    if (eip != NULL) {
        Dl_info info;
        if (dladdr(eip, &info) != 0) {
            serverLog(LL_WARNING|LL_RAW,
                "\n------ DUMPING CODE AROUND EIP ------\n"
                "Symbol: %s (base: %p)\n"
                "Module: %s (base %p)\n"
                "$ xxd -r -p /tmp/dump.hex /tmp/dump.bin\n"
                "$ objdump --adjust-vma=%p -D -b binary -m i386:x86-64 /tmp/dump.bin\n"
                "------\n",
                info.dli_sname, info.dli_saddr, info.dli_fname, info.dli_fbase,
                info.dli_saddr);
            size_t len = (long)eip - (long)info.dli_saddr;
            unsigned long sz = sysconf(_SC_PAGESIZE);
            if (len < 1<<13) { /* we don't have functions over 8k (verified) */
                /* Find the address of the next page, which is our "safety"
                 * limit when dumping. Then try to dump just 128 bytes more
                 * than EIP if there is room, or stop sooner. */
                unsigned long next = ((unsigned long)eip + sz) & ~(sz-1);
                unsigned long end = (unsigned long)eip + 128;
                if (end > next) end = next;
                len = end - (unsigned long)info.dli_saddr;
                serverLogHexDump(LL_WARNING, "dump of function",
                    info.dli_saddr ,len);
                dumpX86Calls(info.dli_saddr,len);
            }
        }
    }

    serverLogRaw(LL_WARNING|LL_RAW,
"\n=== REDIS BUG REPORT END. Make sure to include from START to END. ===\n\n"
"       Please report the crash by opening an issue on github:\n\n"
"           http://github.com/redis/redis/issues\n\n"
"  Suspect RAM error? Use redis-server --test-memory to verify it.\n\n"
);

    /* free(messages); Don't call free() with possibly corrupted memory. */
    if (server.daemonize && server.supervised == 0) unlink(server.pidfile);

    /* Make sure we exit with the right signal at the end. So for instance
     * the core will be dumped if enabled. */
    sigemptyset (&act.sa_mask);
    act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND;
    act.sa_handler = SIG_DFL;
    sigaction (sig, &act, NULL);
    kill(getpid(),sig);
}
#endif /* HAVE_BACKTRACE */

/* ==================== Logging functions for debugging ===================== */

void serverLogHexDump(int level, char *descr, void *value, size_t len) {
    char buf[65], *b;
    unsigned char *v = value;
    char charset[] = "0123456789abcdef";

    serverLog(level,"%s (hexdump of %zu bytes):", descr, len);
    b = buf;
    while(len) {
        b[0] = charset[(*v)>>4];
        b[1] = charset[(*v)&0xf];
        b[2] = '\0';
        b += 2;
        len--;
        v++;
        if (b-buf == 64 || len == 0) {
            serverLogRaw(level|LL_RAW,buf);
            b = buf;
        }
    }
    serverLogRaw(level|LL_RAW,"\n");
}

/* =========================== Software Watchdog ============================ */
#include <sys/time.h>

void watchdogSignalHandler(int sig, siginfo_t *info, void *secret) {
#ifdef HAVE_BACKTRACE
    ucontext_t *uc = (ucontext_t*) secret;
#else
    (void)secret;
#endif
    UNUSED(info);
    UNUSED(sig);

    serverLogFromHandler(LL_WARNING,"\n--- WATCHDOG TIMER EXPIRED ---");
#ifdef HAVE_BACKTRACE
    logStackTrace(uc);
#else
    serverLogFromHandler(LL_WARNING,"Sorry: no support for backtrace().");
#endif
    serverLogFromHandler(LL_WARNING,"--------\n");
}

/* Schedule a SIGALRM delivery after the specified period in milliseconds.
 * If a timer is already scheduled, this function will re-schedule it to the
 * specified time. If period is 0 the current timer is disabled. */
void watchdogScheduleSignal(int period) {
    struct itimerval it;

    /* Will stop the timer if period is 0. */
    it.it_value.tv_sec = period/1000;
    it.it_value.tv_usec = (period%1000)*1000;
    /* Don't automatically restart. */
    it.it_interval.tv_sec = 0;
    it.it_interval.tv_usec = 0;
    setitimer(ITIMER_REAL, &it, NULL);
}

/* Enable the software watchdog with the specified period in milliseconds. */
void enableWatchdog(int period) {
    int min_period;

    if (server.watchdog_period == 0) {
        struct sigaction act;

        /* Watchdog was actually disabled, so we have to setup the signal
         * handler. */
        sigemptyset(&act.sa_mask);
        act.sa_flags = SA_SIGINFO;
        act.sa_sigaction = watchdogSignalHandler;
        sigaction(SIGALRM, &act, NULL);
    }
    /* If the configured period is smaller than twice the timer period, it is
     * too short for the software watchdog to work reliably. Fix it now
     * if needed. */
    min_period = (1000/server.hz)*2;
    if (period < min_period) period = min_period;
    watchdogScheduleSignal(period); /* Adjust the current timer. */
    server.watchdog_period = period;
}

/* Disable the software watchdog. */
void disableWatchdog(void) {
    struct sigaction act;
    if (server.watchdog_period == 0) return; /* Already disabled. */
    watchdogScheduleSignal(0); /* Stop the current timer. */

    /* Set the signal handler to SIG_IGN, this will also remove pending
     * signals from the queue. */
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    act.sa_handler = SIG_IGN;
    sigaction(SIGALRM, &act, NULL);
    server.watchdog_period = 0;
}
